<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="./css/index.css" />
    <title>记事本</title>
  </head>
  <body>
    <!-- 主体区域 -->
    <section id="app">
      <!-- 输入框 -->
      <header class="header">
        <h1>小黑记事本</h1>
        <input v-model="taskName" placeholder="请输入任务" class="new-todo" />
        <button class="add" @click="add">添加任务</button>
      </header>
      <!-- 列表区域 -->
      <section class="main">
        <ul class="todo-list">
          <!-- 写了 v-for 顺手把 :key 也加上 -->
          <li v-for="(v, i) of taskList" :key="v.id" class="todo">
            <div class="view">
              <span class="index">{{ i + 1 }}.</span>
              <label>{{ v.name }}</label>
              <button class="destroy" @click="del(v.id)"></button>
            </div>
          </li>
        </ul>
      </section>
      <!-- 统计和清空 -->
      <footer class="footer" v-show="taskList.length > 0">
        <!-- 统计 -->
        <span class="todo-count"
          >合 计:<strong> {{ taskList.length }} </strong></span
        >
        <!-- 清空 -->
        <button class="clear-completed" @click="clear">清空任务</button>
      </footer>
    </section>

    <!-- 底部 -->
    <script src="../vue.js"></script>
    <script>
      const app = new Vue({
        el: '#app',
        data: {
          taskName: '', // 新增的任务名
          taskList: [
            { id: 1, name: '吃饭饭' },
            { id: 2, name: '喝水水' },
          ],
        },
        methods: {
          clear() {
            // this.taskList = []; // 新数组（内存地址变了）
            this.taskList.splice(0); // 原数组（内存地址没变）
          },
          add() {
            if (this.taskName.trim() === '') return;

            // 1. 获取到输入框中任务名
            // 2. 添加到数组中
            // 3. 清空输入框

            this.taskList.push({
              // id: Date.now(),
              id: Math.max(0, ...this.taskList.map(v => v.id)) + 1,
              name: this.taskName,
            });

            this.taskName = '';
          },
          del(id) {
            this.taskList = this.taskList.filter(v => v.id !== id);
          },
        },
      });
    </script>
  </body>
</html>
